The first edition was basically a translation of Steve Perrin's Basic Role-Playing (which in turn is based on RuneQuest) combined with the Magic World booklet.
The second Edition was published in 1984, rewriting the text from scratch, fixing many translation errors and glitches in the rules although no other major changes were made. One of the available player races, the anthropomorphic ducks, was incorporated from Glorantha.
The transition to a new system of rules began in 1985, not with the third edition which mostly corrected spelling errors, but with the publication of an "Expert" rule expansion: Drakar och Demoner Expert. This among other things introduced hit locations and the use of a 20-sided die instead of the percentile die for skill rolls.
The fourth edition in 1991 was a major revision of the rules, superseding Drakar och Demoner Expert by incorporating it into the basic rules and then expanding them.
In 1994, Target Games released a fifth edition. This version was notable mainly because it came with an integrated world description. Changes to rules was minor, mostly reflecting the new campaign setting.
In the late 1990s, Target Games found itself in financial difficulties and discontinued their line of role-playing games. The rights to Drakar och Demoner were transferred to Paradox Entertainment, who in turn licensed them to Riotminds. Riotminds published a new version of the game in 2000. This sixth edition was a complete overhaul of the game rules, supporting a much less generic game world. The idea of "Expert" rules was re-used, and many rules expansions followed.
When Riotminds released their first take on the venerable Drakar och Demoner ruleset, it featured a concept very close to levels ("yrkesnivåer"). It didn't take long before an official addendum appeared on their website, with optional rules on how to play without this feature. In the subsequent reprints (as well as later editions) little or no traces of "yrkesnivåer" remain.